Précédent|Prochain

Digital beamforming in the elevation of Spaceborne SAR assisted by DEM data

  • role： First author第一作者
  • Affiliation：

    Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China

    University of the Chinese Academy of Sciences, Beijing 100049, China

  • Email：yekai_seven@hotmail.com
  • Introduction：叶恺，1988年生，男，博士研究生，研究方向为新体制星载SAR系统设计和信号处理。E-mail：yekai_seven@hotmail.com
YE Kai12,  
  • Affiliation：

    Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China

    University of the Chinese Academy of Sciences, Beijing 100049, China

YU Weidong12,  
  • Affiliation：

    Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China

WANG Wei1

résumé

Digital Beam Forming (DBF) in elevation plays a crucial role in spaceborne Synthetic Aperture Radar (SAR) by realizing the high-resolution wide-swath (HRWS) imaging mode. However, when dealing with echo signals in mountainous and relief areas, the traditional scan-on-receive (SCORE) approach in elevation always leads to the problem of beam mispointing. This problem leads to the reduction of system receiving gain, which affects the imaging performance of SAR systems. To address the problem of beam mispointing, this work proposes a DBF processing approach in elevation based on Digital Elevation Map (DEM). This work presents a detailed analysis on the steering direction of the DBF receiving beam. A processing procedure for the proposed approach consisting of three main steps is elaborated. First, on the basis of spaceborne SAR imaging geometry, the height of the target is computed for each range cell in SAR imagery by using the DEM data and satellite orbit parameters. Second, the direction of arrival (DOA) angle of the target is calculated for each range cell with the geometry model of earth. Third, according to the relationship between DOA angle of target and each range cell, the DBF weighted coefficients are computed for each range cell. This step enables the receiving beam to point to the signal source of the real target, thereby improving the receiving gain of echo signals. Finally, an X-band spaceborne SAR system is introduced for simulation experiments. Simulation results show that when the ground height is more than 1.9 km, the amplitude of the target signal processed by the traditional SCORE method is attenuated more than 2.8 dB. After the proposed method is used, the target signal amplitude is attenuated less than 0.4 dB. Thus, the proposed method is superior to the traditional SCORE method. The influence of DEM error on the DBF processing method in elevation is also analyzed. As the acquired DEM data have adequate height accuracy, DEM errors have minimal influence on the proposed approach. Taking full consideration of spaceborne SAR imaging geometry model and DEM data of the ground scene, the proposed method can correct the DBF receiving beam pointing deviation in mountainous areas. The proposed method has the potential to promote the application of DBF processing in spaceborne SAR.

mots-clés

synthetic aperture radar;high-resolution wide-swath;digital beamforming;digital elevation map;receiving gain

References

  1. 1.
    Bordoni F, Younis M, Varona E M and Krieger G. 2009. Adaptive digital beam-forming algorithm for high-resolution, wide-swath synthetic aperture radar//International Radar Symposium. Berlin, Germany: [s.n.]: 1-5
  2. 2.
    Bueso-Bello J L, Martone M, Prats-Iraola P and Bräutigam B. 2016. First characterization and performance evaluation of bistatic TanDEM-X experimental products. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 9(3): 1058–1071
  3. 3.
    Chen E X. 2004. Study on Ortho-rectification Methodology of Space-borne Synthetic Aperture Radar Imagery. Beijing: Chinese Academy of Forestry: 123-150
  4. 4.
    Cumming I G and Wong F H. 2005. Digital Processing of Synthetic Aperture Radar Data: Algorithms and Implementation. Norwood, MA: Artech House: 3-168
  5. 5.
    Curlander J C. 1982. Location of Spaceborne SAR imagery. IEEE Transactions on Geoscience and Remote Sensing, GE-20(3): 359-364
  6. 6.
    Freeman A, Johnson W T K, Huneycutt B, Jordan R, Hensley S, Siqueira P and Curlander J. 2000. The " Myth” of the minimum SAR antenna area constraint. IEEE Transactions on Geoscience and Remote Sensing, 38(1): 320–324
  7. 7.
    Gruber A, Wessel B, Huber M, Breunig M, Wagenbrenner S and Roth A. 2012. Quality assessment of first TanDEM-X DEMs for different terrain types//Proceedings of the 9th European Conference on Synthetic Aperture Radar. Nuremberg: IEEE: 101-104
  8. 8.
    Krieger G, Gebert N and Moreira A. 2008. Multidimensional waveform encoding: a new digital beamforming technique for synthetic aperture radar remote sensing. IEEE Transactions on Geoscience and Remote Sensing, 46(1): 31–46
  9. 9.
    Krieger G, Huber S, Villano M, De Almeida F Q, Younis M, Lopez-Dekker P, Prats P, Rodriguez-Cassola M and Moreira A. 2016. SIMO and MIMO system architectures and modes for high-resolution ultra-wide-swath SAR imaging//Proceedings of EUSAR 2016: 11th European Conference on Synthetic Aperture Radar. Hamburg, Germany: IEEE: 1-6
  10. 10.
    Krieger G, Moreira A, Fiedler H, Hajnsek I, Werner M, Younis M and Zink M. 2007. TanDEM-X: a satellite formation for high-resolution SAR interferometry. IEEE Transactions on Geoscience and Remote Sensing, 45(11): 3317–3341
  11. 11.
    Krieger G, Younis M, Gebert N, Huber S, Bordoni F, Patyuchenko A and Moreira A. 2010. Advanced concepts for high-resolution wide-swath SAR imaging//Proceedings of the 8th European Conference on Synthetic Aperture Radar. Aachen, Germany: IEEE: 1-4
  12. 12.
    Moreira A, Krieger G, Hajnsek I, Papathanassiou K, Younis M, Lopez-Dekker P, Huber S, Villano M, Pardini M, Eineder M, De Zan F and Parizzi A. 2015. Tandem-L: a highly innovative bistatic SAR mission for global observation of dynamic processes on the earth’s surface. IEEE Geoscience and Remote Sensing Magazine, 3(2): 8–23
  13. 13.
    Rabus B, Eineder M, Roth A and Bamler R. 2003. The shuttle radar topography mission——a new class of digital elevation models acquired by spaceborne radar. ISPRS Journal of Photogrammetry and Remote Sensing, 57(4): 241–262
  14. 14.
    Suess M, Grafmueller B and Zahn R. 2001. A novel high resolution, wide swath SAR system//Proceedings of the Scanning the Present and Resolving the Future. Proceedings of the IEEE 2001 international Geoscience and Remote Sensing Symposium. Sydney, NSW, Australia: IEEE: 1013-1015
  15. 15.
    Suess M and Wiesbeck W. 2001. Side-looking synthetic aperture radar system. European Patent, EP1241487B1
  16. 16.
    Varona E M. 2009. Adaptive Digital Beam-forming for High-resolution Wide-swath Synthetic Aperture Radar. Barcelona: University Politècnica of Catalonia: 31-42
  17. 17.
    Younis M, Fischer C and Wiesbeck W. 2003. Digital beamforming in SAR systems. IEEE Transactions on Geoscience and Remote Sensing, 41(7): 1735–1739
  18. 18.
    Younis M, Huber S, Patyuchenko A, Bordoni F and Krieger G. 2009. Performance comparison of reflector- and planar-antenna based digital beam-forming SAR. International Journal of Antennas and Propagation, 2009: 614931

Lire l'article complet

The above content is generated by Large Model Translation. The translated content is for reference only. We do not assume any commercial or legal responsibilty for any consequences arising from the use of our website